The present invention relates to a method of controlling access to an area accessible by persons, particularly to a space closed by a door. For performance of the method a first mobile communications unit on which at least one access code is filed and a receiver unit for receiving the access code are provided. The receiver unit serves for checking the access code and frees access after a successful checking of the access code.
Modern access control systems of buildings are frequently operated by a chipcard on which an electronic key is filed. Apart from this electronic key, user-specific data such as, for example, a personal visit card or the like can also be stored on a chipcard of that kind. In addition, the data on the chipcard can be provided with an expiry date so that use of the chipcard is possible only for a specific period of time. However, the disadvantage exists with a chipcard of that kind, particularly when this forms the sole control authority of the door lock, that the chipcard can be passed on to an unauthorized third party or lost.
Some solutions for this problem are already known from the state of the art. Thus, US published patent application 2002/0180582 A1, for example, describes a method of controlling access to an environment locked by a lock, wherein a first access code is stored in a first memory unit and a second access code is stored in a second memory unit of an electronic key unit. The electronic key unit, which is preferably formed by a mobile telephone, communicates the second access code to a control unit of the lock. The communicated second access code is subsequently compared with the first access code stored in the first memory unit and, if the first access code agrees with the second access code, the lock is released. The mobile telephone is in that case equipped in such a manner that the second memory unit can store a plurality of access codes for a number of buildings. In this way the user can make a selective choice of an access code and communicate this to the control unit of the lock equipment.
It has proved disadvantageous with this known method that the access code stored on the mobile telephone is usable only by a user who is in possession of the mobile telephone and knows the PIN code for switching the mobile telephone to be free. This is usually in that case one and the same person. For this reason the access right in the form of the access code is transmissible to a third party only in the case of handing over the mobile telephone and making known the PIN code to the third party.